Solanum is a very large genus of plants typified by nightshade, but also including potatoes, tomatoes, and eggplant (aubergine). Scores of other food plants are included in this genus, but most are grown in tropical climates. The green parts of many plants in the genus are poisonous to humans.
The structure of the genus is under debate, and many plants have been grouped into subgenus or sections of their own.
Most uses of the term Solanum in gardening refer to tomatoes, eggplants, and potatoes as a general group in crop rotation, as they enjoy more acidic soil. After growing Solanums, it is recommended to add compost and fresh dolomite lime to the area and rotate to Brassicas and salad greens the following year.